Fixture suspending phonograph record blank



June 9, .1959

B. J. HUNTING ETAL' 2,890,160

FIXTURE SUSPENDING PHONOGRAPH RECORD BLANK Filed Oct. '27, 1955 INVENTORS BERNARDUS JACOBUS HUNTING ANNE RINIEMA HENDRIK OVEREEM AGE T United States Patent FIXTURE SUSPENDING PHONOGRAPH RECORD BLANK Bernardus Jacobus Hunting and Anne Rinzema, Baarn, Netherlands, and Hendrik Overeem, deceased, late of Baarn, Netherlands, by Joris Daniel Heijligers, executor, Baarn, Netherlands, assignors, by mesne assignments, to North American Philips Company, Inc, New York, N.Y., a corporation of Delaware Application October 27, 1955, Serial No. 543,104

Claims priority, application Netherlands November 8, 1954 3 Claims. (Cl. 204-281) This invention relates to fixtures for phonograph record wax blanks or matrices for suspending them during electro-deposition in an electrolyte solution in such manner that the side not to be coated of the blank or matrix is shielded in a liquid-tight manner.

It is necessary to secure the aforesaid blanks or matrices for electro-deposition to a bar or the like, since they must be freely suspended in an electrolyte solution during electro-deposition. Moreover, it is often desirable that the blanks or the matrices should rotate in the electrolyte solution. By means of the bar secured to the blank or the matrix said rotation can be imparted to it in a simple manner.

In a conventional method of attachment, the ends of a bent brass strip are soldered to the blank or to the matrix at both sides of the center respectively. Suspension may be effected by means of a screw bolt which is secured to the central part of the strip.

The aforesaid method of attachment suifers from a limitation in that the electrolyte solution penetrates through a central hole of the blank or matrix so that deposition of the electrolyte solution also occurs at the edges of the hole and at the side not to be coated in the immediate vicinity of the hole. In order to strip the deposited layer from the blank or matrix the aforesaid hole requires to be bored out. It has been proposed to seal said hole by means of a rubber stop, but this did not yield satisfactory results.

Owing to unavoidable heating the aforesaid usual attachment gives rise to stresses at the central part of the blank or matrix, thus causing unevenesses which are also present in the electro-formed print.

Attempts have been made to improve the aforesaid r attachment by inserting a bolt in the central hole. In this case, however, it is necessary to cover the bolt with a. layer of tin at both sides of the blank or matrix, in order to prevent the electrolyte solution from penetrating between the bolt and the blank or matrix and depositing at the edges of the hole and in its immediate proximity on the side not to be coated, thus likewise causing unevenesses at the central part.

The present invention has for its object to mitigate said disadvantages.

In accordance with the invention, the blank or the matrix has a central conical hole in which a bolt having a conical head is tightened by means of a nut. This attachment is mechanically suflicient to transmit rotation from the bar to the blank or the matrix. Moreover, the hole of the blank or matrix is closed in a liquid-tight manner by the conical head of the bolt, thus avoiding undue deposits. It has been found that the bolts used in accordance with the invention can be used many times, thus obtaining a saving in cost. According to the conventional method of attachment the strips were often damaged on loosening the blank or the matrix so that they had to be replaced.

According to a further feature of the invention the liquid-tight seal of the hole of the matrix or blank can be improved by providing a ring with a conical hole between the blank or matrix and the nut, which yields an additional closure over the conical head.

Moreover, the invention permits in a very simple mariner of centering the grooves of the blank or the matrix to be also imparted to the electro-formed print. According to a further feature of the invention the head of the bolt comprises a central point which causes a cavity in the print and permits orientation for centering the print.

in order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawing, given by way of example, in which Fig. 1 shows the attachment of a record wax blank or matrix to a bar, and

Fig. 2 is a detail view on a larger scale of the attachment shown in Fig. 1.

A sound record blank or matrix 1 has a conical hole 2 in which a bolt 3 with a screw thread 4 and a conical head 5 is tightened by means of a nut 6: A ring 7 having a conical hole 8 is arranged between the nut 6 and the matrix 1. The head 5 of the bolt 3 is provided with a central point 9. The upper side of the matrix 1 is covered with soft rubber 10 which in turn is shielded by a plate 11 at its upper side. The bolt 3 is secured to a suspension bar 12 comprising a hard rubber trunk 13 at its lower end. The rubber covering 10, the plate 11 and the trunk 13 yield a liquid-tight closure at the upper side of the matrix 1. The conical head 5 also closes the hole 2 in a liquid-tight manner.

What is claimed is:

1. A device suspending phonograph record blanks in an electrolytic solution whereby one surface of the record blank not to be coated is shielded from said electrolytic solution in a liquid tight manner comprising; a record blank having a central, conical-shaped hole, a screwthreaded bolt having a head correspondingly shaped to said central, conical-shaped hole and seated therein, the exposed surface of said head being generally planar and flush with the other surface of said record blank, and a nut rotatably engaging the screw threads of said bolt and abutting the one surface of said record blank not to be coated by said electrolytic solution, said nut rendering said one surface free from said electrolytic solution.

2. A device suspending phonograph record blanks as claimed in claim 1 further comprising a ring arrangement located between said one surface and said nut.

3. A device for suspending phonograph record blanks as claimed in claim 1 further comprising a centrally located projection extending from the plane surface of the head of said screw-threaded bolt for the centering and proper orientation of an electro-formed record.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Italy Mar. 27, 1943 

1. A DEVICE SUSPENDING PHONOGRAPH RECORD BLANKS IN AN ELECTROLYTIC SOLUTION WHEREBY ONE SURFACE OF THE RECORD BLANK NOT TO BE COATED IS SHIELDED FROM SAID ELECTROLYTIC SOLUTION IN A LIQUID TIGHT MANNER COMPRISING; A RECORD BLANK HAVING A CENTRAL, CONICAL-SHAPED HOLE, A SCREWTHREADED BOLT HAVING A HEAD CORRESPONDINGLY SHAPED TO SAID CENTRAL, CONICAL-SHAPED HOLE AND SEATED THEREIN, THE EXPOSED SURFACE OF SAID HEAD BEING GENERALLY PLANAR AND FLUSH WITH THE OTHER SURFACE OF SAID RECORD BLANK, AND A NUT ROTATABLY ENGAGING THE SCREW THREADS OF SAID BOLT AND ABUTTING THE ONE SURFACE OF SAID RECORD BLANK NOT TO BE COATED BY SAID ELECTROLYTIC SOLUTION, SAID NUT RENDERING SAID ONE SURFACE FREE FROM SAID ELECTROLYTIC SOLUTION. 